Communication apparatus

a communication apparatus and multi-carrier technology, applied in the field of communication apparatus and multi-carrier transmission system, can solve the problems of transmission channel estimation, which is carried out in the receiving device, cannot follow sufficiently to instantaneous fluctuation and periodical fluctuation of wide-band noise, and achieve the effect of enhancing transmission efficiency

Active Publication Date: 2007-11-27
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The solution enables robust transmission channel estimation and improved transmission efficiency by adapting to various fluctuations in the power line channel, enhancing carrier detection and synchronization accuracy.

Problems solved by technology

In the meantime, in a conventional system, there was such a problem that transmission channel estimation, which is carried out in a receiving device, can not follow sufficiently to instantaneous fluctuation and periodical fluctuation of wide-band noise or narrow-band noise, or instantaneous fluctuation and periodical fluctuation which come up with amplitude fluctuation and phase fluctuation of a transmission channel itself, when transmission channel estimation is simply carried out only once in a certain cycle, in a power line transmission channel.
As described above, in a multi-carrier power line communication apparatus which used the conventional wavelet, it has such a problem that transmission channel estimation, which is carried out in a receiving device, cannot follow sufficiently to instantaneous fluctuation and periodical fluctuation of wide-band noise or narrow-band noise, or instantaneous fluctuation and periodical fluctuation which come up with amplitude fluctuation and phase fluctuation of a transmission channel itself, when transmission channel estimation is simply carried out only once in a certain cycle, in a power line transmission channel.

Method used

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embodiment 2

[0050]FIG. 4 is a block diagram which shows a receiving device in an embodiment 2 of this invention. In passing, a transmitting device is the same as the transmitting device 299 of FIG. 19.

[0051]In addition, a difference between the receiving devices of FIG. 4 and of FIG. 1 is only an AGC (Automatic Gain Control) circuit 390. Since other circuits are the same as the circuits which were explained in FIG. 1, descriptions are pursuant to the descriptions in the embodiment 1. 390 designates an AGC circuit which automatically adjust a gain of a reception signal. Next, by use of FIG. 4 and FIG. 5, an operation in case that this system was applied to the power line communication will be described. FIG. 5 is a view which shows a noise characteristic in case that wide-band noise was added in a power line transmission channel.

[0052]A difference from the embodiment 1 is to carry out noise detection by the noise detector 360 including a gain which is used by the AGC circuit.

[0053]In the embodim...

embodiment 3

[0058]A channel estimation unit in an embodiment 3 of this invention will be described. In this embodiment, a receiving device, and a transmitting device of a communication apparatus are the same as in the embodiment 1 or 2.

[0059]FIG. 7 shows a frame configuration view in case of carrying out transmission channel estimation by use of time of a power supply cycle.

[0060]Next, an operation will be described. FIG. 6 shows a frame configuration view for explaining an operation of a normal channel estimation unit.

[0061]Normally, as shown in FIG. 6, a transmission channel estimation frame is added in a frame to be transmitted and received (in the figure, a “CE frame” is the “transmission channel estimation frame”).

[0062]Generally speaking, in a transmission channel estimating method of the suchlike configuration, this transmission channel estimation frame is used again on an irregular basis, when a transmission channel fluctuates significantly, and if a past transmission channel estimation...

embodiment 4

[0069]The channel estimation unit 370, which is used in a communication apparatus in an embodiment 4 of this invention, will be described.

[0070]In this embodiment, by use of the configuration / operation of the communication apparatus of the embodiment 3, transmission channel estimation is carried out in a certain cycle.

[0071]Further additionally, the channel estimation unit 370 in this embodiment, in case that, at that time, fluctuation of noise and fluctuation of a transmission channel exist in 1 cycle, but in each sub carrier, influence of transmission channel fluctuation is smaller than a threshold value (in case that it does not have influence on errors), becomes to maintain good transmission efficiency by use of that sub carrier even if there is fluctuation.

[0072]By realizing the suchlike configuration, as compared to the communication apparatus in the embodiment 3, it becomes possible to further heighten transmission efficiency.

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Abstract

A communication apparatus has an A / D converter which converts an analog signal which was received, into a digital signal, a converter which converts a reception signal so as to enable handling of phase information, a carrier detector which detects presence or absence of the reception signal, a synchronous circuit which extract synchronization timing from the reception signal, an equalizer which corrects the reception signal so as to cancel influence of a transmission path, a transmission path estimator which estimates a state of a power line transmission path, and a judging unit which judges the reception signal, which was amended by the equalizer, by use of a threshold value.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to a communication apparatus and a communication method using multi-carrier transmission system, particularly, to a communication apparatus and a communication method which used a multi-carrier transmission system (Digital Wavelet Multi Carrier transmission system, hereinafter, referred to as DWMC transmission system) which carries out data transmission by digital modulation and demodulation processing which used a real coefficient wavelet filter bank which is more suitable for a power line transmission channel and a transmission channel such as a telephone line.[0002]As a conventional technology which has been frequently used in the multi-carrier transmission system, there are FFT (Fast Fourier Transform) based OFDM (Orthogonal Frequency Division Multiplexing) and Wavelet based OFDM. Such an example that these technologies were applied to power line communication is disclosed in (JP-A-11-163807). The wavelet base has a resista...

Claims

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Application Information

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Patent Type & AuthorityPatents(United States)
IPC IPC(8): H04B1/06H04B7/00H04B1/00H04J11/00H04B1/16H04B3/06H04B3/54H04B14/02H04L1/00H04L1/18H04L25/02H04L25/03H04L27/00H04L27/26
CPCH04B3/54H04B14/023H04L5/0046H04L25/03159H04L27/0004H04L27/2601H04B2203/5416H04B2203/5425H04B2203/5491H04L1/0009H04L2025/03414H04L25/022H04L1/18
InventorKOGA, HISAOKODAMA, NOBUTAKAKONISHI, TAISUKE
OwnerPANASONIC CORP